A nurse is educating a client with sinusitis about the correct use of nasal decongestants. What should the nurse emphasize?

A. Avoid combining with antihistamines: Many allergy regimens safely combine decongestants for acute relief with antihistamines for long-term symptom control. There is no contraindication to using these two classes together to address different pathways of the allergic response. They provide additive benefits for the patient. B. Take every 4 hours regardless of symptoms: Decongestants should be used sparingly and only when symptomatic to minimize systemic absorption and local irritation. Frequent, scheduled dosing increases the risk of side effects like tachycardia and hypertension. Using them on an "as-needed" basis is the safer clinical approach. C. Discontinue as soon as symptoms resolve: While this is true for most symptomatic treatments, the specific instruction for decongestants must focus on the maximum duration of use. Even if symptoms persist, the patient must stop after 5 days to avoid rebound effects. The duration of therapy is more critical than the resolution of symptoms. D. Use for no more than 3 to 5 days: Intranasal sympathomimetics provide rapid relief by constricting nasal blood vessels, but prolonged use leads to down-regulation of alpha-adrenergic receptors. This results in severe rebound vasodilation and mucosal edema when the drug is stopped. Limiting use prevents the development of rhinitis medicamentosa.